Homogeneously catalyzed depolymerization of lignin from organosolv medium: Characterization, optimization, and minimization of coke formation

Abstract

This study focused on maximizing yields of oligomeric and monomeric products while minimizing coke formation in the depolymerization of lignin from an organosolv medium. A design of experiments (DoE) with temperature, time, and ethanol‐water ratio as factors was established and tested. Optimized reaction conditions were found at 185.4°C with 7.5 wt% sodium hydroxide as catalyst, an ethanol‐water ratio of 48.6% (v/v), and a residence time of 30 minutes. With these optimized parameters, maximum monomer and oligomer yields of 9.4 wt% and 86.2 wt% and minimized coke formation of 0.5 wt% were achieved. The oligomeric and monomeric products were characterized by GPC, GC‐MS, and OH‐group determination (Folin‐Ciocalteu).

Techno‐economic and life‐cycle assessment of a wood chips‐based organosolv biorefinery concept for production of lignin monomers and oligomers by base‐catalyzed depolymerization

“…12 Süss et al optimized a system by designing an experiment in which organosolv lignin was successfully depolymerized in a water/ethanol solvent by sodium hydroxide, and almost all coke formation was suppressed. 13 In this and similar reports, the monomeric phase mostly consists of a wide variety of phenolic substances, which are often found in low concentrations. [14][15][16] These low concentrations, the variety of monomers, and the chemical similarity make separation processes complex and economically unfeasible.…”

“…For the conceptual BCD, data from laboratory results, provided by Süss et al, were upscaled. 13 The data for the ReUse-process design was obtained in the laboratory by the same authors, Süss et al, by repeating the works described by them 13 followed by the novel ReUse work-up approach. Details are found in the Appendix S1.…”

“…The inputs and yields for the depolymerization of lignin were linearly scaled up from the work of Süss et al, with the exception of the solvent use, which decreased by 20%, as advised by Piccinno et al 25 The experimental laboratory parameters and derived simulation parameters are listed in Table 2. 13,27 Subsequently, the reaction parameters were kept equivalent to laboratory conditions, meaning that a temperature of 185.4 °C was maintained for 30 min. Thermal energy consumption was modeled using Eqn (1), as derived from Piccinno et al 27 A reactor with a capacity of 10 000 L was modeled as the reaction vessel.…”

“…This is justifiable because of the low char yields of 0.5% reported by Süss et al and the low number and mass average (Mn & Mw) values reported. 13…”

Investigation of Selective Extraction of Phenolic Compounds and of Saccharides From Picea Abies Bark Using Organosolv Solvents

“…The extraction and purification of these desired compounds is the key tasks. Organosolv solvents are the preferred process media for biorefining lignocellulosic feedstocks, such as wood [4]. Thus, it is worthwhile to also look to valorize the bark extract by means of organosolv media.…”